János Móczó - Profile on Academia.edu (original) (raw)
Papers by János Móczó
Szabályozott méretű, illetve nano részecskékkel társított polimerek előállítása és vizsgálata: adhézió, módosítás, deformációs mechanizmusok = Preparation and study of polymers combined with nanoparticles or fillers of controlled particle size: adhesion, modification, deformation mechanisms
Modification of interfacial adhesion with a functionalized polymer in PLA/wood composites
European Polymer Journal, 2015
ABSTRACT Maleic anhydride (MA) grafted poly(lactic acid) (PLA) coupling agents (MAPLA) were prepa... more ABSTRACT Maleic anhydride (MA) grafted poly(lactic acid) (PLA) coupling agents (MAPLA) were prepared by reactive processing. The amount of peroxide initiator and MA was varied over a relatively wide range. Coupling efficiency was checked in PLA/wood composites as a function of grafting degree, coupling agent and wood content. The analysis of the results showed that chain scission takes place in PLA during reactive modification. The occurrence of grafting could not be proved by FTIR spectroscopy, but a detailed NMR analysis showed that the degree of grafting depends on the amount of both reactants; a maximum of 2.5 MA groups/PLA chain could be grafted under the conditions used in the study. The functionalized polymer proved to be an efficient coupling agent in PLA/wood composites. Efficiency increased with increasing number of functionality and coupling agent amount. Coupling resulted in increased strength and reinforcement. Acoustic emission analysis of deformation processes supported by microscopy proved that the dominating local deformation process is the fracture of the fibers, but a small extent of debonding also occurs in neat, uncoupled composites. The prevention of debonding by coupling resulted in the improved performance of the composites. Local processes initiate the immediate failure of the composite irrespectively of their mechanism.
Wood fiber reinforced multicomponent, multiphase PP composites: Structure, properties, failure mechanism
Composites Science and Technology, 2014
ABSTRACT
Factors determining the performance of thermoplastic polymer/wood composites; the limiting role of fiber fracture
Materials & Design, 2014
ABSTRACT Thermoplastic polymer/lignocellulosic fiber composites were prepared with a considerable... more ABSTRACT Thermoplastic polymer/lignocellulosic fiber composites were prepared with a considerable range of matrices and fibers in an internal mixer. Tensile properties were determined on bars cut from compression molded plates. Local deformation processes initiated around the fibers were followed by acoustic emission testing supported by electron and polarization optical microscopy. The analysis of results proved that micromechanical deformation processes initiated by the fibers determine the performance of the composites. Debonding usually leads to the decrease of composite strength, but decreasing strength is not always associated with poor adhesion and debonding. The direction of property change with increasing wood content depends on component properties and interfacial adhesion. Good interfacial adhesion often results in the fracture of the fibers. Depending on their size and aspect ratio, fibers may fracture parallel or perpendicular to their axis. At good adhesion, the maximum strength achieved for a particular polymer/wood pair depends on the inherent strength of the fibers, which is larger for perpendicular than parallel fracture. Inherent fiber strength effective in a composite depends also on particle size, larger particles fail at smaller stress, because of the larger number of possible flaws in them. A very close correlation exists between the initiation stress of the dominating local deformation process and composite strength proving that these processes lead to the failure of the composite and determine its performance.
Polymer/Wood Composites
Wiley Encyclopedia of Composites, 2011
ABSTRACT
Adsorption of surfactants on CaCO3 and its effect on surface free energy
Progress in Colloid and Polymer Science, 2004
ABSTRACT
Express Polymer Letters, 2009
Composites were prepared from poly(lactic acid) (PLA) and a natural CaSO4 filler to study the dev... more Composites were prepared from poly(lactic acid) (PLA) and a natural CaSO4 filler to study the developed structure and the interaction of the components. The filler was characterized very thoroughly by several techniques and the results indicated that the filler contains a considerable amount of small particles with size much below the volume average size of 4.4 μm. The presence of these small particles did not result in inhomogeneity, considerable extent of aggregation was not observed in the composites. The filler was coated with stearic acid to modify interactions and optimum coverage corresponded to the amount estimated from the specific surface area of the filler. Mechanical properties changed only slightly with increasing amounts of the uncoated filler, but coating resulted in a drastic change of tensile properties and deformation behavior. Considerable plastic flow was observed around filler particles on the fracture surface of broken specimens. The quantitative estimation of interfacial interactions and their comparison to existing data proved that the interaction of PLA and CaSO4 corresponds to values observed in other mineral filled polymers. On the other hand, the reinforcing effect of the coated filler is extremely poor indicating almost zero interaction. Additional experiments proved that considerable amount of stearic acid dissolves in PLA and plasticizes the polymer. Stearic acid seems to desorb also from the surface of the filler, dissolve in the polymer and modify matrix properties.
Wood flour filled PP composites: adhesion, deformation, failure
Polymers for Advanced Technologies, 2006
Abstract Poly (propylene)(PP) wood composites were prepared in a wide composition range from 0 to... more Abstract Poly (propylene)(PP) wood composites were prepared in a wide composition range from 0 to 70 wt% wood content. Matrix/wood adhesion was improved by the introduction of two maleinated polypropylenes (MAPPs) with different molecular weights and functionality ...
Wood flour filled polypropylene composites: Interfacial adhesion and micromechanical deformations
Polymer Engineering & Science, 2007
ABSTRACT
Micromechanical deformation processes in PA/layered silicate nanocomposites: Correlation of structure and properties
Polymer Engineering & Science, 2007
... According to the results of XRD measurements (Fig. 2), the silicate modified with the ali-pha... more ... According to the results of XRD measurements (Fig. 2), the silicate modified with the ali-phatic amine exfoliates in a larger extent than the one organophilized with the amino acid, and TEM micro-graphs also indicate considerable exfoliation. ...
Effect of desiccant characteristics on the properties of PS/zeolite functional packaging materials
Polymer Composites, 2014
ABSTRACT
Polymer, 2010
Volume strain measurements of particulate filled polypropylene (PP) composites containing differe... more Volume strain measurements of particulate filled polypropylene (PP) composites containing different glass beads and talc as filler were carried out in tension as a function of temperature and strain rate to determine the micro-mechanisms of deformation. While local cavitation mechanisms (micro-voiding, crazing, and micro-cracking) and subsequent debonding of the particles dominated as failure mechanisms at high strain rates and at room temperature, a more significant contribution of local shear yielding was observed with a reduced contribution of cavitational mechanisms at low strain rates or at 80 C. This change in the dominating micro-mechanisms of deformation resulted in smaller volume strains during the tensile loading of the composites than for the respective neat matrix. Moreover, a novel approach is introduced for the detection of debonding using volume strain measurements, which takes into account the dilatational and deviatoric behavior of the neat matrix polymer and the composite. The results are supported by acoustic emission measurements carried out simultaneously on the same specimens.
Morphology and Properties of Particulate Filled Polymers
Macromolecular Symposia, 2004
ABSTRACT
Aggregation of particulate fillers: factors, determination, properties
Macromolecular Symposia, 2003
... 194,111-124 (2003) 111 Aggregation of Particulate Fillers: Factors, Determination, Properties... more ... 194,111-124 (2003) 111 Aggregation of Particulate Fillers: Factors, Determination, Properties Jónos Móczó12, Erika Fekete1'2, Krisztina Làszló3, Béla Pukánszky12* 'institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest ... Vörös, В ...
Effect of Clay Modification on the Mechanism of Local Deformations in PA6 Nanocomposites
Macromolecular Materials and Engineering, 2013
ABSTRACT AbstractPA nanocomposites are prepared from clays organophilized with a phosphonium and ... more ABSTRACT AbstractPA nanocomposites are prepared from clays organophilized with a phosphonium and an ammonium salt, and sodium montmorillonite is used as reference. The analysis of mechanical and micromechanical properties of the composites reveal that several micromechanical deformation processes occur in the PA/MMT composites. The matrix cavitates at relatively small stress. Processes related to non‐exfoliated clay structural units are initiated at larger stresses. Sound is emitted mainly by the fracture of particles, but debonding may also occur. The plastic deformation of the matrix dominates at larger stresses and deformations. The various local deformations are independent of each other and composite properties are not determined by silicate related processes but by the deformation of the matrix.
Journal of Industrial and Engineering Chemistry, 2008
The characteristics of all heterogeneous polymer systems including composites containing either m... more The characteristics of all heterogeneous polymer systems including composites containing either micro or nanofillers are determined by four factors: component properties, composition, structure and interfacial interactions. The most important filler characteristics are particle size, size distribution, specific surface area and particle shape, while the main matrix property is stiffness. Segregation, aggregation and the orientation of anisotropic particles determine structure. Interfacial interactions lead to the formation of a stiff interphase considerably influencing properties. Interactions are changed by surface modification, which must be always system specific and selected according to its goal. Under the effect of external load inhomogeneous stress distribution develops around heterogeneities, which initiate local micromechanical deformation processes determining the macroscopic properties of the composites. In filled polymers the dominating deformation mechanism is usually debonding. Nanocomposites represent one of the new classes of materials, but further research and development is needed before they gain significant position in the market.
Determination of the surface characteristics of particulate fillers by inverse gas chromatography at infinite dilution: a critical approach
Journal of Colloid and Interface Science, 2004
CaCO3 fillers were investigated by inverse gas chromatography (IGC) to determine the dispersion c... more CaCO3 fillers were investigated by inverse gas chromatography (IGC) to determine the dispersion component of their surface tension as well as their acid-base character. Because of the high energy of the filler surface, it readily adsorbs water, thus the parameters measured by IGC depend on the conditioning temperature, as well as on the measurement conditions. As a consequence, the determined surface characteristics are not material constants; different fillers or the effect of coating can be compared only under standard conditions. The use of the same conditioning and measurement temperature eliminates the effect of measurement time. Under appropriate standard conditions the acid-base characteristics of the filler can be determined reliably. However, the accuracy of the determination and the value of the derived parameters depend very much on the selected approach and on the acid-base constants used for the probe molecules. A critical analysis of the approaches used in the current literature pointed out those that yield the most reasonable and accurate values. The results prove that the surface of CaCO3 is strongly basic in character. Coating significantly reduces basicity. Surprisingly, the filler coated with an amount of stearic acid resulting in minimum surface tension showed relatively strong acidity, which indicates a coating exceeding monolayer coverage and/or the uneven distribution of the surfactant on the surface.
PLA/lignocellulosic fiber composites: Particle characteristics, interfacial adhesion, and failure mechanism
Journal of Applied Polymer Science, 2014
ABSTRACT
Acid-Base Interactions and Interphase Formation in Particulate-Filled Polymers
The Journal of Adhesion, 2002
Particulate-filled composites were prepared from CaCO 3 and polymer matrices of various acid-base... more Particulate-filled composites were prepared from CaCO 3 and polymer matrices of various acid-base characters. Interfacial interaction of the components was characterized by the reversible work of adhesion, which was calculated either from dipole-dipole or acid-base interactions. The thickness of the spontaneously formed interlayer was derived from the tensile strength of the composites. The results proved that acid-base interactions play an
European Polymer Journal, 2005
Polypropylene (PP) model composites were prepared using cross-linked PMMA particles with a very n... more Polypropylene (PP) model composites were prepared using cross-linked PMMA particles with a very narrow particle size distribution as filler in order to study the micromechanical processes, which take place during deformation. Composites containing a commercial CaCO 3 filler with a broad particle size distribution were also prepared and studied for comparison. The filler loading of the composites was changed from 0 to 0.3 volume fraction in 0.05 volume fraction steps. Measurements of acoustic emission signals during the elongation of PP/PMMA model composites allowed us to assign the debonding process, including its initiation, unambiguously to a well-defined section of the stress vs. strain curve. The number and intensity of the acoustic signals detected during the deformation of the matrix polymer and the composite, respectively, differed considerably, which made possible the separation of the various micromechanical deformation processes occurring in them. At low extensions the composite is deformed elastically, then debonding takes place in a very narrow deformation range, followed by the plastic deformation of the matrix. At small particle content debonding occurs at relatively low stresses, which differ significantly from the yield stress. Considerable plastic deformation of the matrix begins at the yield point. At larger filler content debonding and shear yielding occur simultaneously. Micromechanical deformation processes cannot be separated as clearly in composites prepared from the commercial CaCO 3 filler with a broad particle size distribution. The debonding of particles with different size occurs in a wide deformation range because of the particle size dependence of debonding stress. The analysis of characteristic values derived from acoustic emission experiments proved that the interacting stress fields of neighboring particles influence the deformation process and that even large particles may aggregate or at least associate at large filler content.
Szabályozott méretű, illetve nano részecskékkel társított polimerek előállítása és vizsgálata: adhézió, módosítás, deformációs mechanizmusok = Preparation and study of polymers combined with nanoparticles or fillers of controlled particle size: adhesion, modification, deformation mechanisms
Modification of interfacial adhesion with a functionalized polymer in PLA/wood composites
European Polymer Journal, 2015
ABSTRACT Maleic anhydride (MA) grafted poly(lactic acid) (PLA) coupling agents (MAPLA) were prepa... more ABSTRACT Maleic anhydride (MA) grafted poly(lactic acid) (PLA) coupling agents (MAPLA) were prepared by reactive processing. The amount of peroxide initiator and MA was varied over a relatively wide range. Coupling efficiency was checked in PLA/wood composites as a function of grafting degree, coupling agent and wood content. The analysis of the results showed that chain scission takes place in PLA during reactive modification. The occurrence of grafting could not be proved by FTIR spectroscopy, but a detailed NMR analysis showed that the degree of grafting depends on the amount of both reactants; a maximum of 2.5 MA groups/PLA chain could be grafted under the conditions used in the study. The functionalized polymer proved to be an efficient coupling agent in PLA/wood composites. Efficiency increased with increasing number of functionality and coupling agent amount. Coupling resulted in increased strength and reinforcement. Acoustic emission analysis of deformation processes supported by microscopy proved that the dominating local deformation process is the fracture of the fibers, but a small extent of debonding also occurs in neat, uncoupled composites. The prevention of debonding by coupling resulted in the improved performance of the composites. Local processes initiate the immediate failure of the composite irrespectively of their mechanism.
Wood fiber reinforced multicomponent, multiphase PP composites: Structure, properties, failure mechanism
Composites Science and Technology, 2014
ABSTRACT
Factors determining the performance of thermoplastic polymer/wood composites; the limiting role of fiber fracture
Materials & Design, 2014
ABSTRACT Thermoplastic polymer/lignocellulosic fiber composites were prepared with a considerable... more ABSTRACT Thermoplastic polymer/lignocellulosic fiber composites were prepared with a considerable range of matrices and fibers in an internal mixer. Tensile properties were determined on bars cut from compression molded plates. Local deformation processes initiated around the fibers were followed by acoustic emission testing supported by electron and polarization optical microscopy. The analysis of results proved that micromechanical deformation processes initiated by the fibers determine the performance of the composites. Debonding usually leads to the decrease of composite strength, but decreasing strength is not always associated with poor adhesion and debonding. The direction of property change with increasing wood content depends on component properties and interfacial adhesion. Good interfacial adhesion often results in the fracture of the fibers. Depending on their size and aspect ratio, fibers may fracture parallel or perpendicular to their axis. At good adhesion, the maximum strength achieved for a particular polymer/wood pair depends on the inherent strength of the fibers, which is larger for perpendicular than parallel fracture. Inherent fiber strength effective in a composite depends also on particle size, larger particles fail at smaller stress, because of the larger number of possible flaws in them. A very close correlation exists between the initiation stress of the dominating local deformation process and composite strength proving that these processes lead to the failure of the composite and determine its performance.
Polymer/Wood Composites
Wiley Encyclopedia of Composites, 2011
ABSTRACT
Adsorption of surfactants on CaCO3 and its effect on surface free energy
Progress in Colloid and Polymer Science, 2004
ABSTRACT
Express Polymer Letters, 2009
Composites were prepared from poly(lactic acid) (PLA) and a natural CaSO4 filler to study the dev... more Composites were prepared from poly(lactic acid) (PLA) and a natural CaSO4 filler to study the developed structure and the interaction of the components. The filler was characterized very thoroughly by several techniques and the results indicated that the filler contains a considerable amount of small particles with size much below the volume average size of 4.4 μm. The presence of these small particles did not result in inhomogeneity, considerable extent of aggregation was not observed in the composites. The filler was coated with stearic acid to modify interactions and optimum coverage corresponded to the amount estimated from the specific surface area of the filler. Mechanical properties changed only slightly with increasing amounts of the uncoated filler, but coating resulted in a drastic change of tensile properties and deformation behavior. Considerable plastic flow was observed around filler particles on the fracture surface of broken specimens. The quantitative estimation of interfacial interactions and their comparison to existing data proved that the interaction of PLA and CaSO4 corresponds to values observed in other mineral filled polymers. On the other hand, the reinforcing effect of the coated filler is extremely poor indicating almost zero interaction. Additional experiments proved that considerable amount of stearic acid dissolves in PLA and plasticizes the polymer. Stearic acid seems to desorb also from the surface of the filler, dissolve in the polymer and modify matrix properties.
Wood flour filled PP composites: adhesion, deformation, failure
Polymers for Advanced Technologies, 2006
Abstract Poly (propylene)(PP) wood composites were prepared in a wide composition range from 0 to... more Abstract Poly (propylene)(PP) wood composites were prepared in a wide composition range from 0 to 70 wt% wood content. Matrix/wood adhesion was improved by the introduction of two maleinated polypropylenes (MAPPs) with different molecular weights and functionality ...
Wood flour filled polypropylene composites: Interfacial adhesion and micromechanical deformations
Polymer Engineering & Science, 2007
ABSTRACT
Micromechanical deformation processes in PA/layered silicate nanocomposites: Correlation of structure and properties
Polymer Engineering & Science, 2007
... According to the results of XRD measurements (Fig. 2), the silicate modified with the ali-pha... more ... According to the results of XRD measurements (Fig. 2), the silicate modified with the ali-phatic amine exfoliates in a larger extent than the one organophilized with the amino acid, and TEM micro-graphs also indicate considerable exfoliation. ...
Effect of desiccant characteristics on the properties of PS/zeolite functional packaging materials
Polymer Composites, 2014
ABSTRACT
Polymer, 2010
Volume strain measurements of particulate filled polypropylene (PP) composites containing differe... more Volume strain measurements of particulate filled polypropylene (PP) composites containing different glass beads and talc as filler were carried out in tension as a function of temperature and strain rate to determine the micro-mechanisms of deformation. While local cavitation mechanisms (micro-voiding, crazing, and micro-cracking) and subsequent debonding of the particles dominated as failure mechanisms at high strain rates and at room temperature, a more significant contribution of local shear yielding was observed with a reduced contribution of cavitational mechanisms at low strain rates or at 80 C. This change in the dominating micro-mechanisms of deformation resulted in smaller volume strains during the tensile loading of the composites than for the respective neat matrix. Moreover, a novel approach is introduced for the detection of debonding using volume strain measurements, which takes into account the dilatational and deviatoric behavior of the neat matrix polymer and the composite. The results are supported by acoustic emission measurements carried out simultaneously on the same specimens.
Morphology and Properties of Particulate Filled Polymers
Macromolecular Symposia, 2004
ABSTRACT
Aggregation of particulate fillers: factors, determination, properties
Macromolecular Symposia, 2003
... 194,111-124 (2003) 111 Aggregation of Particulate Fillers: Factors, Determination, Properties... more ... 194,111-124 (2003) 111 Aggregation of Particulate Fillers: Factors, Determination, Properties Jónos Móczó12, Erika Fekete1'2, Krisztina Làszló3, Béla Pukánszky12* 'institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest ... Vörös, В ...
Effect of Clay Modification on the Mechanism of Local Deformations in PA6 Nanocomposites
Macromolecular Materials and Engineering, 2013
ABSTRACT AbstractPA nanocomposites are prepared from clays organophilized with a phosphonium and ... more ABSTRACT AbstractPA nanocomposites are prepared from clays organophilized with a phosphonium and an ammonium salt, and sodium montmorillonite is used as reference. The analysis of mechanical and micromechanical properties of the composites reveal that several micromechanical deformation processes occur in the PA/MMT composites. The matrix cavitates at relatively small stress. Processes related to non‐exfoliated clay structural units are initiated at larger stresses. Sound is emitted mainly by the fracture of particles, but debonding may also occur. The plastic deformation of the matrix dominates at larger stresses and deformations. The various local deformations are independent of each other and composite properties are not determined by silicate related processes but by the deformation of the matrix.
Journal of Industrial and Engineering Chemistry, 2008
The characteristics of all heterogeneous polymer systems including composites containing either m... more The characteristics of all heterogeneous polymer systems including composites containing either micro or nanofillers are determined by four factors: component properties, composition, structure and interfacial interactions. The most important filler characteristics are particle size, size distribution, specific surface area and particle shape, while the main matrix property is stiffness. Segregation, aggregation and the orientation of anisotropic particles determine structure. Interfacial interactions lead to the formation of a stiff interphase considerably influencing properties. Interactions are changed by surface modification, which must be always system specific and selected according to its goal. Under the effect of external load inhomogeneous stress distribution develops around heterogeneities, which initiate local micromechanical deformation processes determining the macroscopic properties of the composites. In filled polymers the dominating deformation mechanism is usually debonding. Nanocomposites represent one of the new classes of materials, but further research and development is needed before they gain significant position in the market.
Determination of the surface characteristics of particulate fillers by inverse gas chromatography at infinite dilution: a critical approach
Journal of Colloid and Interface Science, 2004
CaCO3 fillers were investigated by inverse gas chromatography (IGC) to determine the dispersion c... more CaCO3 fillers were investigated by inverse gas chromatography (IGC) to determine the dispersion component of their surface tension as well as their acid-base character. Because of the high energy of the filler surface, it readily adsorbs water, thus the parameters measured by IGC depend on the conditioning temperature, as well as on the measurement conditions. As a consequence, the determined surface characteristics are not material constants; different fillers or the effect of coating can be compared only under standard conditions. The use of the same conditioning and measurement temperature eliminates the effect of measurement time. Under appropriate standard conditions the acid-base characteristics of the filler can be determined reliably. However, the accuracy of the determination and the value of the derived parameters depend very much on the selected approach and on the acid-base constants used for the probe molecules. A critical analysis of the approaches used in the current literature pointed out those that yield the most reasonable and accurate values. The results prove that the surface of CaCO3 is strongly basic in character. Coating significantly reduces basicity. Surprisingly, the filler coated with an amount of stearic acid resulting in minimum surface tension showed relatively strong acidity, which indicates a coating exceeding monolayer coverage and/or the uneven distribution of the surfactant on the surface.
PLA/lignocellulosic fiber composites: Particle characteristics, interfacial adhesion, and failure mechanism
Journal of Applied Polymer Science, 2014
ABSTRACT
Acid-Base Interactions and Interphase Formation in Particulate-Filled Polymers
The Journal of Adhesion, 2002
Particulate-filled composites were prepared from CaCO 3 and polymer matrices of various acid-base... more Particulate-filled composites were prepared from CaCO 3 and polymer matrices of various acid-base characters. Interfacial interaction of the components was characterized by the reversible work of adhesion, which was calculated either from dipole-dipole or acid-base interactions. The thickness of the spontaneously formed interlayer was derived from the tensile strength of the composites. The results proved that acid-base interactions play an
European Polymer Journal, 2005
Polypropylene (PP) model composites were prepared using cross-linked PMMA particles with a very n... more Polypropylene (PP) model composites were prepared using cross-linked PMMA particles with a very narrow particle size distribution as filler in order to study the micromechanical processes, which take place during deformation. Composites containing a commercial CaCO 3 filler with a broad particle size distribution were also prepared and studied for comparison. The filler loading of the composites was changed from 0 to 0.3 volume fraction in 0.05 volume fraction steps. Measurements of acoustic emission signals during the elongation of PP/PMMA model composites allowed us to assign the debonding process, including its initiation, unambiguously to a well-defined section of the stress vs. strain curve. The number and intensity of the acoustic signals detected during the deformation of the matrix polymer and the composite, respectively, differed considerably, which made possible the separation of the various micromechanical deformation processes occurring in them. At low extensions the composite is deformed elastically, then debonding takes place in a very narrow deformation range, followed by the plastic deformation of the matrix. At small particle content debonding occurs at relatively low stresses, which differ significantly from the yield stress. Considerable plastic deformation of the matrix begins at the yield point. At larger filler content debonding and shear yielding occur simultaneously. Micromechanical deformation processes cannot be separated as clearly in composites prepared from the commercial CaCO 3 filler with a broad particle size distribution. The debonding of particles with different size occurs in a wide deformation range because of the particle size dependence of debonding stress. The analysis of characteristic values derived from acoustic emission experiments proved that the interacting stress fields of neighboring particles influence the deformation process and that even large particles may aggregate or at least associate at large filler content.